1. Field of the Invention
This invention relates to a new method of producing 1-(4'-isobutylphenyl)ethanol (IBPE).
2. Background Information
The compound 2-(4'-isobutylphenyl)propionic acid, more commonly known as ibuprofen, is a well-known nonsteroidal anti-inflammatory drug which has been converted from ethical, i.e., prescription, to over-the-counter status.
A recently proposed method of producing ibuprofen is disclosed in pending U.S. patent application Ser. No. 028,514, filed Mar. 20, 1988, by Elango et al, involves the carbonylation of IBPE under prescribed conditions using any of certain palladium-containing catalysts. Also disclosed in this application is the preparation of IBPE by the hydrogenation of 4-isobutylacetophenone (IBAP) using any of various hydrogenation catalysts, including Raney nickel.
Activated sponge nickel, e.g., Raney nickel, which is a widely used type of hydrogenation catalyst, is pyrophoric, i.e., it tends to ignite spontaneously in the presence of air. Because of this, it is stored and shipped submerged in a liquid which effectively protects it from contact with air. The most common type of protective liquid used for this purpose is composed preponderantly of water, e.g., water containing a small amount of dissolved alkaline material, e.g., sodium hydroxide.
3. Description of Related Art
The following information is disclosed in accordance with the terms of 37 CFR 1.56, 1.97 and 1.98.
Japanese Kokai Patent No. SHO 55 [1980]-27147, published Feb. 27, 1980, and assigned to Mitsubishi Petrochemical Co., discloses the formation of aryl-substituted carboxylic acids, e.g., ibuprofen, by reacting an aryl-substituted alcohol, e.g., IBPE, with carbon monoxide and water in the presence of a hydrogen fluoride catalyst. Also disclosed generally is the synthesis of the aryl-substituted alcohol by reducing the corresponding ketone.
Czech Patent No. CS 219,752 of Sept. 15, 1985, discloses a process of making ibuprofen from isobutylbenzene including the step of reducing IBAP to IBPE using lithium aluminum hydride as reductant.
D. P. Curran, J. Am. Chem. Soc. 1983, 105, 5826-5833, discloses the reduction of isoxazolines to beta-hydroxy ketones using Raney nickel as catalyst and aqueous methanol as solvent. The washing of Raney nickel free of hydroxide with 20-30 water washes prior to use is shown on page 5830.
M. Delepine et al, Bull. Soc. Chim. France, 1937, 31-49, teach the preparation of aromatic carbinols such as methylphenylcarbinol and ethylphenylcarbinol by hydrogenation of the corresponding ketone using Raney nickel promoted with alkali as catalyst, and ethyl alcohol as solvent.
M. Freifelder et al, J. Pharm. Sci. 53, 967 (1964), teach the preparation of 1-phenylethanol by hydrogenation of acetophenone using Raney nickel promoted with alkali as catalyst and ethyl alcohol as solvent.
M. Freifelder, Catalytic Hydrogenation in Organic Synthesis--Procedures and Commentary, John Wiley, New York (1978), pages 81-89, discloses the use of Raney nickel as catalyst for the hydrogenation of various aromatic aldehydes and ketones to the corresponding alcohols, e.g., acetophenone to 1-phenyl-1-ethanol in ethyl alcohol as solvent. On page 83, the reference states that Raney nickel "may well be the one of choice for the reduction of aromatic aldehydes and ketones . . . "
L. Kotlyarevskii et al, Khim. prom., 1981 (7), 391-393, translated in Soviet Chemical Industry, 13:7, 813-819 (1981), disclose a process of synthesizing p-divinylbenzene, including the step of reducing p-diacetylbenzene (p-DAB) using Raney nickel as catalyst, to produce "1-4-bis(.alpha.-oxyethyl)benzene."
D. Nightingale et al, J. Org. Chem. 14, 1089-1093 (1949), teach at page 1090 the hydrogenation of various aromatic ketones using Raney nickel as catalyst to produce the corresponding carbinol and aromatic hydrocarbon.
G. G. Hawley, Condensed Chemical Dictionary, 10th Ed., Van Nostrand Reinhold, New York (1959), page 883, and M. Windholz, Ed., The Merck Index, 10th Ed., Merck & Co., Rahway, NJ (1983), p. 8019, show that Raney nickel is pyrophoric and is generally stored under a protective liquid such as water.